Gas turbine engine blades

ABSTRACT

A gas turbine blade has a hollow interior space which is divided to form flow passages for cooling medium. The flow passages are bounded by the sides of a sheet-like insert the two blade walls, and fins between the insert and the blade walls; they commence at one end of the blade and extend in a spiral-like path around the opposite sides of the insert.

United States Patent 1191 Moore 1 Apr. 23, 1974 [54] GAS TURBINE ENGINE BLADES 3,370,829 2/1968 Banthin et a1. 416 97 3,527,544 9/1970 Allen 416/97 UX [751 Invenm 3mm, Engla'ld 3,606,574 9/1971 Brands et al 416/97 x 1 3,628,880 12/1971 Smuland et a1 416/97 X [73] Asslgnee 53223 252; F 3,635,587 1/1972 Giesman et 111. 416/97 [22] Aug 22 1972 FOREIGN PATENTS OR APPLICATIONS [21] Appl No 282 778 853,534 10/1952 Germany 416/96 Primary Examiner Everette A. Powell, Jr. [30] Foreign Application Priority Data Attorney, Agent, or Firm-Stevens, Davis, Miller &

Aug. 25, 1971 Great Britain 39778/71 Mosher Aug, 25, 1971 Great Britain 39778/71 57 ABSTRACT [52] US. Cl. 416/97 1 51 1m. (:1. F01d 5/18 A gas turbme blade has a hollow Interim 1 9 which [58 Field 6: Search 416/96-97, is divided form flow Passages cooling medium- 416/92 The flow passages are bounded by the sides of a sheetlike insert the two blade walls, and fins between the [56] References Cited insert and the blade walls; they commence at one end UNITED STATES PATENTS of the blade and extend in a spiral-like path around the opposite sides of the insert. 2,888,243 5/1959 Pollock 416/92 1 3 3,057,597 10/ 1962 Meyer et a1... 416/96 12 Claims, 3 Drawing Figures 1 GAS TURBINE ENGINE BLADES This invention relates to the blading of gas turbine engines, and although not so limited, has particular reference to rotor blades for such engines.

As is known, it is advantageous to provide for the cooling of gas turbine rotor blades, and many different ways of doing this are known. In particular, it is known to provide a cooling air flow through the interior of the blade, and the cooling is the more effective, the greater the volume of air flow and the greater the velocity of the air as it passes through the blade.

In very small rotor blades, e.g., less than 1% inches long considerable difficulties are encountered in providing flow channels by means of which satisfactory cooling can be achieved. The present invention aims to provide a rotor or stator blade construction which enables improved cooling to be obtained.

An object of the invention is to provide an improved a gas-turbine blade with a hollow interior space which is divided to form flow passages bounded by the sides of a sheet-like insert, the two blade walls and fins between the insert and the blade walls, the flow passages commencing at one end of the blade and extending in a spiral-like path around and along the insert.

In a preferred form, the invention is applied to rotor blades which are fed from the root end.

The invention will now be described with reference to the accompanying drawing, in which:

FIG. 1 shows a sectional elevation of a gas turbine rotor blade according to the invention, the section blade is hollow, and the space within it is effectively di-' vided into two by means of a sheet-metal insert 14 which extends substantially the full radial length of the blade being brazed to the blade at its root end but otherwise unattached to allow for differential expansion. The arrangement of the insert 14 within the blade is clearly seen in FIG. 2.

It will be seen that the insert is located between a large number of pimples 15 (indicated in FIG. 1 by small crosses) and by a series of helical fins 16. The

blade is conveniently made with the pimples and fins cast onto the interior surfaces of the blade walls l7, 18.

The insert 14 stops short of both the leading and trailing edges of they blade, thus leaving spaces around which air may pass in order to progress from,one side of the insert to the other.

Referring new again to FIG. 1, it will be seen that air suppliedto the interior of the blade from the root end 13 can enter any one of a series of flow passages extending obliquely up one side of the insert passing round the leading or trailing edge of the insert, and then continuing obliquely up the other side of the insert. An arrow traces one possible path. As it pro gresses radially outwards, a proportion of the air is allowed to escape through leading edge film cooling holes 20, and'through trailing edge slots 21. Since the volume of air flowing through the blade is thus diminished, the flow passages are designed to be of smaller cross section towards the outer shroud end 12 of the blade. This can be achieved by arranging that the spacing of the fins 16 is reduced or,'mor'e conveniently, by reducing the width of the passages. This maintains the airflow velocity substantially constant. In addition, the velocity of the air flow may be varied by altering the angle at which the fins 16 arecast onto the interior surfacesof the blade.

In a preferred form of the invention, holes 22 (FIG! 3) may be provided for the final escape of the cooling air in the angle formed by the blade proper wall 17 and the shroud 23. The air thus released can be used to cool the shroudby causing it to spread over the shroud 23 along channels 24 formed in the radially inner surface thereof.

lt will be seen that a blade constructed in the fashion described is relatively easy to produce, particularly since the insert is solid and therefore easy both to manufacture and to insert into the blade, while the blade itself can be conveniently cast, together with, fins and pimples, using only a single piece core.

. If desired, in the described arrangement the holes 20 and/or the holes 21 and/or the pimples 15 may be omit ted, the cooling medium may be liquid or a gas other than air, and the fins 16 and'pimples (if provided) may be other than integral with the blade walls.

In a further variation of the described arrangement at least some of the flow passages for cooling air are such that they individually serve either the leading edge of the blade or the trailing edge of the blade, but not both. This may be effected by suitable choice of the inclination of the fins 16. Such an arrangement may enable different supplies to be used for the leading and trailing edges of the blade to make allowance for the different ambient air pressures existing in those regions.

. What is claimed is:

l. A gas turbine blade having opposed walls defining therebetween a hollow interior space, an insert within said space, said insert being formed of a solid sheet curved to the chamberof the blade, and fins carried by said blade and extending between said insert and said blade walls, said walls, said-insert and said fins defining in combination a plurality of flow passages for cooling fluid, each said flow passage commencing at one end of the blade and extending in a spiral-like manner around and along the insert.

2. A blade as claimed in claim 1, which includes a plurality of discrete pimples extending between the sides of the insert and the blade walls within the flow passages for providing location for the insert.

3. A blade as claimed in claim 2, wherein the fins and pimples are formed integrally with. the blade walls. 4. A blade as claimed in claim 1, wherein holes are formed in the region of the leading edge of the blade for allowing cooling fluid to pass to the exterior of the blade from the flow passages.

5. A blade as claimed in claim 1, wherein holes are formed in the region of the trailing edge of the blade for allowing cooling fluid to pass to the exterior of the blade from the flowpassages.

6. A blade as claimed in claim 1, wherein the insert has a root end portion at which it is secured within the blade by brazing, the insert being otherwise unattached to allow for differential expansion. I l

7. A blade as claimed in claim 1, wherein at least some of the flow passages are arranged for individually serving one edge only of the blade.

8. A gas turbine rotor having a plurality of blades as claimed in claim 1, arranged for supply with cooling fluid at their root ends.

9. A gas turbine rotor according to claim 8, which includes a shroud connecting together the outer ends of 5 are terminated immediately adjacent said root end portion of said insert.

12 A gas turbine blade having opposed walls defining therebetween a hollow interior space, and an insert within said space, said insert being formed of a solid sheet curved to the chamber of the blade and connected to said walls by brazing at the root end of the blade, being otherwise unattached to allow for differential expansion, said walls being integrally formed with fins extending between said insert and said blade walls, said walls, said insert and said fins defining in combination a plurality of flow passages for cooling fluid to flow through the blade commencing at the root end of 'the blade and passing in a spiral-like manner around and along the insert. 

1. A gas turbine blade having opposed walls defining therebetween a hollow interior space, an insert within said space, said insert being formed of a solid sheet curved to the chamber of the blade, and fins carried by said blade and extending between said insert and said blade walls, said walls, said insert and said fins defining in combination a plurality of flow passages for cooling fluid, each said flow passage commencing at one end of the blade and extending in a spiral-like manner around and along the insert.
 2. A blade as claimed in claim 1, which includes a plurality of discrete pimples extending between the sides of the insert and the blade walls within the flow passages for providing location for the insert.
 3. A blade as claimed in claim 2, wherein the fins and pimples are formed integrally with the blade walls.
 4. A blade as claimed in claim 1, wherein holes are formed in the region of the leading edge of the blade for allowing cooling fluid to pass to the exterior of the blade from the flow passages.
 5. A blade as claimed in claim 1, wherein holes are formed in the region of the trailing edge of the blade for allowing cooling fluid to pass to the exterior of the blade from the flow passages.
 6. A blade as claimed in claim 1, wherein the insert has a root end portion at which it is secured within the blade by brazing, the insert being otherwise unattached to allow for differential expansion.
 7. A blade as claimed in claim 1, wherein at least some of the flow passages are arranged for individually serving one edge only of the blade.
 8. A gas turbine rotor having a plurality of blades as claimed in claim 1, arranged for supply with cooling fluid at their root ends.
 9. A gas turbine rotor according to claim 8, which includes a shroud connecting together the outer ends of the blades, the arrangement being such that cooling fluid may pass from said flow passages into cooling relation with the shroud.
 10. A rotor according to claim 9, wherein the radially inner surface of the shroud is formed with channels, and the blade walls are formed with holes arranged for directing cooling fluid from the flow passages along the channels.
 11. A blade as claimed in claim 6, wherein said fins are terminated immediately adjacent said root end portion of said insert.
 12. A gas turbine blade having opposed walls defining therebetween a hollow interior space, and an insert within said space, said insert being formed of a solid sheet curved to the chamber of the blade and connected to said walls by brazing at the root end of the blade, being otherwise unattached to allow for differential expansion, said walls being integrally formed with fins extending between said insert and said blade walls, said walls, said insert and said fins defining in combination a plurality of flow passages for cooling fluid to flow through the blade commencing at the root end of the blade and passing in a spiral-like manner around and along the insert. 